Wednesday, June 27, 2012

Reception to my first post about the Nº58A front lamp prototype has been great, especially after Chris@Velo_Orangetweeted about it. While waiting for a proper copper heat sink to arrive (and for quotes for a front rack hanging version) I got a new camera that takes nicer photos than my point and shoot. In an effort to learn how it works, I took a series of shots of the Nº58A prototype mounted on my orange bike. The full set is on Flickr.

Friday, June 15, 2012

I've never been much of a Twitter user, evidenced by the sparse tweets on my music-related account. However, Chris was nice enough to link to the Nº58A prototype in the Velo Orange Twitter feed yesterday, which got the attention of a bunch of folks who probably otherwise wouldn't wind up on such an obscure and esoteric corner of the internet. This got me thinking that it was about time to set up an account for Bici Lux. Tweets will likely be few and far between, but I'll probably link to the occasional notable Ebay auction and may tweet out the minutia of designing, engineering and prototyping. So, follow me if you like. It might encourage me to tweet more. twitter.com/bicilux.

Wednesday, June 13, 2012

After an agonizing three month wait (quality budget machinists are busy machinists and never send anything you greatly anticipate through regular mail from Australia to Canada), the parts for the first Nº58A prototype arrived. It was back in February that I first posted about designing a new classically styled bicycle headlight and the prototype was ordered in March.

While I was waiting, I designed and ordered the PCBs for the LED board (with low loss FET rectifier) and stand light board. When they arrived I assembled and tested them. The circuit is very similar to the dynamo standlight I designed for the Sturmey Archer headlamp LED upgrade. It took me a while to find the time to solder the LED to the heat sink, connect the LED and stand light boards and assemble the whole thing into the housing. After fawning over its shininess for a few days, I took a few photos with my lousy point and shoot:

Nº58A

Second hole is for a taillight connection

Right off the bat, there were a couple of problems. The first was that the machinist's supplier substituted brass for the C101/C110 pure copper that was ordered for the heat sink This is a pretty sloppy and annoying transgression for which I was assured the supplier was sufficiently chastised (though it would've been nice if the operator had noticed that he was working with brass when pure copper was specified). Brass is fine for soldering LEDs to but its thermal properties make it unacceptable as an efficient heat sink. Consequently, it took a lot longer to solder the LED as brass isn't nearly as good a conductor of heat as pure copper. For the prototype it should be fine, but I'll need to make sure the heat sink is copper for the next revision.

The second problem is that a slight widening at the opening of the lamp body that was specified in the CAD files wasn't machined. Due to confusion about the female threading it was omitted on the final drawings by mistake and I didn't notice. This widening was to accomodate an o-ring for weather-proofing and without it the o-ring doesn't fit. Again, the next revision will need to have this step cut for the o-ring.

I've had several people suggest making a hanging version that can be mounted on a front rack. This, which will likely be christened the Nº58B, is in the works. In the meantime, the current version is designed to be mounted over the fork crown. Its weight dictates that a heavy duty bracket be used, something like the 4 mm wire bracket offered by Schmidt. Using this bracket, I mounted it on one of my bikes (enjoy the reflections of my living room):

Overall, I'm quite pleased with the results. Everything fits together as it should, with the exception of the bezel's o-ring. I fretted about the location of the switch, but I don't think it's an unacceptable interruption to the lamp's shape. I might try a full switch boot instead of the half boot pictured or perhaps a switch with a shorter actuator.

With a few modifications, this could be ready for a production run if there's enough interest. Before that, I'd like to get the front rack hanging version made and log some serious hours to flush out any design flaws. An asymmetrical version would be nice as the round, flashlight-like beam of the current reflector certainly won't meet the StVZO rules for bicycle lighting. However, for small volume production it seems unlikely that a custom engineered asymmetrical reflector with cutoff will be viable.

Beam shots? Not yet. I personally don't find them very informative, so they are a lower priority. Plus, the LED tested out OK after assembling the lamp, but a few days later it was dead, so I need to replace it which requires waiting for a revised heat sink to get machined. Hopefully this was just an unlucky failure due to the excessive heat required to solder it to the brass heat sink and not because of a systemic design problem. Only testing on the bike will tell...

Tuesday, June 12, 2012

Just a quick note to say that it was time for a little blog layout upgrade to something a little more... contemporary. My HTML days are long behind me and I don't even know what the web runs on nowadays so I had to rely on the fine skills of a friend who wishes to remain anonymous. My thanks to you, whoever you are.

Vintage lighting aficionados will recognize the logo as the armature faceplate of my favorite hub dynamo of all time, the Sturmey Archer GH6 Dynohub.

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About Me

I really like bikes, especially old bikes from the 50s to the 70s. I'm oddly obsessed with dynamo powered bicycle lighting and vintage bicycle lamps and it is here that I try to reconcile these two obsessions. Contact me: jeffrey(dot)lee(at)gmail(dot)com